The research described in this proposal involves development and implementation of a new technique for study of the local structure of biologically important transition metal complexes. The nuclear magnetic resonance spectra of solid samples of the complexes will be taken at low temperatures. The internal dipolar field generated by the unpaired electron spins will lead to large shifts of nuclear resonance signals from nuclei surrounding the metals. Analysis of the nmr shifts will allow us to determine metal-nuclei separations and the local geometry of nuclei surrounding the metal ion. Studies will be conducted with a series of simple model systems and then be expanded to investigations of metal containing proteins, hemoglobins, and nucleic acids. The local structure of ligand molecules near the metal ions in biological processes such as oxygen transport, electron transfer, DNA replication and the synthesis of proteins. Our studies of the local structure of metal complexes should be of great value in determining the mechanism through which the metal complexes function in various biochemical reactions.